Income Taxes (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Deferred:      
Income Tax Expense (Benefit) $ (4.2) $ 3.8  
Long-term deferred tax assets (liabilities), net      
Long-term deferred tax liability, net $ 96.0   $ 101.9
Effective income tax rate (as a percent) 46.20% 90.50%  
Statutory rate (as a percent) 35.00%